抄録
The structure of diatom frustule was transformed to opal-CT just after compression under 100 oC without the morphological change, and then its structure and morphology were retained at least up to 6.9 GPa. With keeping the compression of 5.7 GPa under 100 oC for 7 days, the structure was changed to coesite. After 7 days under 0.3 GPa and 100 oC, the structure of diatom frustule was changed to a mixture of a-moganite and a-quartz, which was an approximately similar texture to chalcedony.
